Although transient cerebral ischemia (TIA) is known to be an important precursor of stroke, there is little information as to the frequency or natural history of this illness in the general community. The purpose of the proposed study is to determine the incidence and prognostic significance of this type of cerebrovascular disease in a large population of elderly retired persons living in Laguna Hills, California. A self-administered questionnaire designed to detect TIA has already been completed by some 11,000, or 63%, of the residents in this community. A three year surveillance of these respondents will be carried out to relate the development of major stroke to the symptoms recorded by the self-administered questionnaire and by a neurologic interview. The information to be obtained from this study should provide important basic information for future intervention efforts aimed at the prevention of stroke.